Plaster colorant system

ABSTRACT

A set of water-soluble film packets each containing one of several available finely ground pigments and, when so desired, an additional amount of finely ground white extender, which are added singly or in any desired multiples to a container of gauging water to which is added a readily available standard quantity of dry cementitious powder, such as plaster, for providing controlled pigmented plaster for precolored plaster walls.

United States Patent [72] lnventor John D. Shull, Jr. Tonawanda, NY. 21Appl. No. 706,920 [22] Filed Feb. 20, 1968 [45] Patented May 25, 1971[73] Assignee National Gypsum Company Buffalo, N.Y.

[54] PLASTER COLORANT SYSTEM 5 Claims, 2 Drawing Figs.

[52] US. Cl 206/46, 53/35, 106/110 [51] Int. Cl B65d 81/00, B65d 85/00[50] Field of Search 206/46 (M), 47 (A), 84, 56 (A), 56 (A2), 0.5;52/309 [56] References Cited UNITED STATES PATENTS 2,528,530 11/1950Machleder Z06/47(A) 2,700,461 1/1955 Smith 206/47(A) 2,719,628 10/1955lvanoff 206/47(A) 2,750,027 6/1956 Cummings 206/0.5 2,819,738 l/1958Marberg 206/47(A) 2,828,858 4/1958 Tooke 206/47(A) 3,111,569 11/1963Rubenstein.... 52/309 3,419,258 12/1968 Ritchie 206/47(A) PrimaryExaminer-William T. Dixson, Jr. Attorney-Robert F. HausePATENIEDHAYZSIEITI 3580.390

DRY PIGMENT WHITE EXTENDER POWDER I POWDER THOROUGH BLENDING 35 GRAMS INWATER SOLUBLE ENVELOPE HEAT-SEALED DISSOLVE IN GAUGING WATER FINISHPLASTER POWDER Mix APPLY Tl NTED FINISH PLASTER Fig.|

INVENTOR. J oh n D. S h u ll ATTORNEY PLASTER COLORANT SYSTEM BACKGROUNDOF THE INVENTION Prior commercial systems for pigmentation of settablecementitious materials suffered from many problems, dependent on theparticular prior system used, to the extent that such prior systems weresubstantially unsuccessful. These problems are generally all related tothe need to be able to produce one batch after another of pigmentedcementitious material without noticeable color variation betweenbatches. Plastering contractors have used dry pigment powders in plastermixes, measuring by level spoonfuls or a level cupful per 50 pound bagof plaster. Even with a high degree of care this will not produceuniformly colored plaster walls. Two different techniques of scoopingpowder out of a container will introduce an intolerable variation inpowder density, in the measuring device, to say nothing of thevariations in making the level spoonful or cupful.

A typical amount of dry pigment powder to be added to a preferred batchof a 50 pound bag of plaster may be as little as about grams, which isabout 0.02 pound. An allowable tolerance of dry pigment has been foundto be about :2 percent, or about -i0.0004 pound. One reason theallowable tolerance is this small is that there are so many othervariations commonly occurring, to be allowed for. The common commercial50 pound bag of plaster, when emptied, will provide 50 pounds, flpercent, or anywhere from about 48.5 to 51.5 pounds of plaster. Commonvariations in the ratio of water to plaster will result in a variationin the ultimate density of the plastered wall, or in other words thearea of wall coverage may vary with a constant thickness of coating.Thus it will be seenhow other large variations, like on the jobmeasurement of 0.02 pound of a dry pigment powder, will inevitablyproduce intolerable total color variations.

Another approach has been the addition of prepared liquid dispersions ofpigment, such as the addition to a batch of plaster of a measured volumeof water-based paint. Here, again, jobsite measuring techniques produceunacceptable variations in color from batch to batch.

Another solution to the problem is to mix, all at once, a sufficientquantity of plaster to complete an entire room. This method issatisfactory for small rooms but creates many obvious problems when thesize of the room is somewhat larger.

SUMMARY OF THE INVENTION The present invention relates to providingfactory sealed packets of measured quantities of dry pigment and whendesired an extender, with the packets being made of watersoluble film,whereby the packet and contents are placed as a unit in the water towhich is added dry cementitious powders for producing a uniformlypigmented cementitious slurry.

DRAWINGS AND DESCRIPTIONS FIG. 1 is a flow chart of the novel process ofthe present invention.

FIG. 2 is an isometric view of a water-soluble packet containingpigment, in accordance with the invention.

In accordance with the invention, a dry powder pigment 10, for use inpreparing tinted finish plaster, is packaged in small water-solubleenvelopes 12, which may be used by simply dissolving the envelope anddispersing the pigment in the water which is to be mixed with the finishplaster powder to form a workable plaster slurry or paste.

The dry powder pigments may be any commonly available, inert dry powder,of a fineness that substantially all passes through a 100 mesh sieve,having color characteristics suitable for producing a desired color whencombined with a gypsum finish plaster, or other inorganic cementitiousmaterial. For example, a series of colors may be provided using selectedcombinations of a series of dry powder pigments sold by Harmon Colors, aDivision of the Allied Chemical Company, and referred to by HarmonColors as Dry Colors.

The development of a desired series of colors to be produced in afinished plaster wall involves, first, the determination of the ratio ofaddition of the basic commercial dry color pigments to one another and,second, the ratio of combined pigments to dry plaster. For example, adesired beige finish plaster may be provided by combining 40 percentyellow pigment, 45 percent orange pigment and 15 percent black pigment,and using 35 grams of the combination per 50 pounds of plaster. Adesired pale green finish plaster may be provided by combining 50percent yellow pigment and 50 percent green pigment and using 14 gramsof the combination per 50 pounds of plaster.

In a preferred form of the invention a series of about eight colors ofdesired finish plaster are selected and ratios of pigments to becombined and ratios of total pigment to plaster are both determined bytrial and error. A batch of combinations of pigment is then thoroughlyblended for each end color to be offered for sale. The batch, for eachend color, is then divided into units of the amount to be used with 50pounds of plaster, since this is a commonly available measured unit ofplaster, such units being per the above examples 35 gram units of thebeige combination of pigments and 14 grams of the pale green combinationof pigments. These units are then each packaged in individual watersoluble filmpackets, as discussed further below.

Alternatively, the above combinations of pigments may be combined andblended with a fine white powder extender. This preferably will be done,in accordance with the invention, to the extent that all of the seriesof colors, as packaged in the packets to be sold, will include an equalweight of dry solids. For example, if the series of colors to bepackaged includes the 35 gram unit of beige combination of pigments, andno combination of pigments requiring more than 35 grams per packet, thenall combinations of pigment requiring less than 35 grams of pigment perpacket are combined with sufficient white extender such that a total of35 grams of blended pigment and extender are packaged in each packet.Thus in preparing the combination of pigments for the above discussedpale green, in accordance with this embodiment, 14 weight units of a50-50 blend of yellow pigment and green pigment are further blendedthoroughly with 21 weight units of white extender powder, whichcombination in then divided into 35 gram units for packaging for usewith 50 pounds of plaster. One advantage is the improved marketacceptability of products with apparently equal material provided ineach of the several different colors offered.

Of greater importance is the advantage of improved quality control byimproved control of the weight tolerance when dividing the finallyblended powders into packet weight units. The tolerance potential of aprocess of dividing the blended material is essentially the same weighttolerance, whether dividing into 14 gram units or into 35 gram units.Accordingly, in a process having a tolerance potential of about 0.7gram, a relatively unacceptable tolerance of fipercent is occasionedwith 14 gram units whereas the tolerance is only a reasonable :2 percentwith 35 gram itnits.

The amount of extender to be added in accordance with the invention maybe such that all colors of a series are extended, if a need for furtherimproved tolerances justifies the increased cost of extender.

A suitable white extender has been found to be finely di' vided calciumcarbonate, such as precipitated calcium carbonate or finely groundlimestone.

The water-soluble packets 12 are preferably made by folding as at 14 andheat-sealing two edges 16,16, prior to filling, and a third edge 18after filling, using a 0.003 inch film of polyethylene oxide. Polyvinylalcohol films, soluble in water, are also suitable.

Having completed a detailed disclosure of the preferred embodiments ofmy invention, so that others may practice the same, I contemplate thatvariations may be made without departing from the essence of theinvention or the scope of the appended claims.

lclaim:

l. A set of pigment packets for coloring cementitious products, said setincluding packets each of which comprises a small packet of awater-soluble thin film, said packets each having sealed therewithin apremeasured weight of dry pigment powder, at least some of said packetscontaining a blended mixture of dry pigment powder and a white extenderpowder, substantially all of the contents of each of said packets beingof a fineness to pass through a 100 mesh sieve, said set includingpackets of substantially different colored pigment combinations, saidpackets of different colored pigment combinations having differentweights respectively of pigment, said packets of said set all havingsubstantially equal weights of combined pigment and white extenderpowder.

2. A set of pigment packets as defined in claim 1 wherein each of saidpackets contains a blended mixture of dry pigment powder and a whiteextender powder.

3. A set of pigment packets as defined in claim 1 wherein the packets ofpigment powder of at least one color are free of said white extenderpowder.

4. A set of pigment packets as defined in claim 1 wherein saidwater-soluble thin film is selected from the class consisting ofpolyethylene oxide and polyvinyl alcohol.

5. A set of pigment packets as defined in claim 1 wherein saidwater-soluble film is of about 0.003 inch thickness.

2. A set of pigment packets as defined in claim 1 wherein each of saidpackets contains a blended mixture of dry pigment powder and a whiteextender powder.
 3. A set of pigment packets as defined in claim 1wherein the packets of pigment powder of at least one color are free ofsaid white extender powder.
 4. A set of pigment packets as defined inclaim 1 wherein said water-soluble thin film is selected from the classconsisting of polyethylene oxide and polyvinyl alcohol.
 5. A set ofpigment packets as defined in claim 1 wherein said water-soluble film isof about 0.003 inch thickness.